Method for the production of an ordered porous structure from an aluminium substrate

Abstract

A method for making a porous structure, includes producing, by anodization of an aluminum substrate, an outer surface layer ( 3 ), part of the thickness of which is formed by an ordered porous structure ( 7 ), characterized in that it includes an anodization step on a smooth aluminum substrate for a duration sufficient for obtaining a thickness of ordered porous structure ( 7 ). The method further includes removing by mechanical machining a portion of the thickness of the layer ( 3 ) formed by anodization, the thickness portion extending from the outer surface of the layer ( 3 ) formed by anodization, while maintaining an ordered porous structure ( 7 ) with a non-zero thickness, so that the ordered porous structure defines the free outer surface of the residual layer.

1 - 16 . (canceled) 
     
     
         17 . Method for the production of a porous structure in which an outer surface layer comprising an ordered porous structure is produced by anodization of an aluminium substrate, whereby:
 an anodization treatment is carried out on a smooth aluminium substrate with a duration sufficient to allow at least a thickness of ordered porous structure to be obtained,   a part of the thickness of the said layer formed by anodization is then removed by mechanical machining, this part of the thickness extending from the outer surface of the said layer formed by anodization, while maintaining at least a non-zero thickness of the ordered porous structure and in a manner such that this ordered porous structure forms the free outer surface of the residual layer.   
     
     
         18 . Method as claimed in  claim 17 , whereby the said part of the thickness is removed by mechanical abrasion. 
     
     
         19 . Method as claimed in  claim 18 , whereby the mechanical abrasion is carried out by means of a piece of fabric impregnated with a suspension, a so-called abrasive suspension, of a powder in an aqueous phase, the said powder comprising at least a mineral chosen from the group of abrasive minerals. 
     
     
         20 . Method as claimed in  claim 18 , whereby the mechanical abrasion is carried out by a plurality of successive abrasion stages, each of the said successive abrasion stages being carried out by means of an abrasive suspension, the abrasive suspensions of each of the successive abrasion stages being chosen in a manner such that a granulometry which decreases from one stage to the other is achieved. 
     
     
         21 . Method as claimed in  claim 20 , whereby each abrasion stage of the plurality of successive abrasion stages is carried out by means of a piece of fabric impregnated with an abrasive suspension, the said piece of fabric being applied to the surface of a rigid support chosen from the group formed by a vibrating support and a rotating support. 
     
     
         22 . Method as claimed in  claim 18 , whereby the mechanical abrasion is carried out by a first abrasion stage by means of a piece of felt impregnated with a suspension of diamond, the mean granulometry of which is between 0.8 μm and 1.5 μm, in particular of the order of 1 μm, and then by a second abrasion stage by means of a piece of felt impregnated with a suspension of diamond, the mean granulometry of which is between 0.2 μm and 0.4 μm, in particular of the order of 0.25 μm. 
     
     
         23 . Method as claimed in  claim 17 , whereby a part of the thickness of the outer surface layer ( 3 ) is removed, the thickness of the said part of the thickness of the outer surface layer being between 15 μm and 25 μm—in particular of the order of from 17 μm to 20 μm. 
     
     
         24 . Method as claimed in  claim 17 , whereby an anodization treatment is carried out on a smooth aluminium substrate with a duration suitable for obtaining an outer surface layer having a thickness of between 25 μm and 300 μm, in particular between 100 μm and 200 μm. 
     
     
         25 . Method as claimed in  claim 17 , whereby a single anodization treatment is carried out on a smooth aluminium substrate, the said treatment having a duration of between 1 h and 12 h, in particular of the order of 4 h. 
     
     
         26 . Method as claimed in  claim 17 , whereby a single anodization treatment is carried out on a smooth aluminium substrate for a duration suitable for the thickness of the ordered porous structure formed by anodization to be between 1 μm and 150 μm. 
     
     
         27 . Method as claimed in  claim 17 , whereby the anodization is carried out in an aqueous solution of electrolyte chosen from the group formed by aqueous solutions of oxidizing acids—in particular sulfuric acid, a mixture of sulfuric acid and boric acid, oxalic acid, phosphoric acid, malonic acid, tartaric acid and citric acid. 
     
     
         28 . Method as claimed in  claim 17 , whereby the anodization is carried out in an aqueous solution of electrolyte, the composition of which is suitable for providing an ordered porous structure, the pores of which have a diameter of between 10 nm and 500 nm, in particular between 100 nm and 200 nm. 
     
     
         29 . Method as claimed in  claim 17 , whereby the anodization is carried out at a temperature of between −2° C. and +2° C.—in particular of the order of −1.5° C. 
     
     
         30 . Method as claimed in  claim 17 , whereby the anodization is carried out under a voltage of between 19 V and 240 V—in particular between 125 V and 195 V, with an aqueous solution containing phosphoric acid as the electrolyte. 
     
     
         31 . Method as claimed in  claim 17 , whereby immediately after having removed the said part of the thickness, the non-oxidized aluminium substrate and a part of the non-porous thickness of the said layer are removed to preserve only the ordered porous structure. 
     
     
         32 . Method as claimed in  claim 17 , whereby a chemical treatment is then carried out on the ordered porous structure which is suitable for increasing the diameter of the pores of the said porous structure. 
     
     
         33 . Method as claimed in  claim 19 , whereby the mechanical abrasion is carried out by a plurality of successive abrasion stages, each of the said successive abrasion stages being carried out by means of an abrasive suspension, the abrasive suspensions of each of the successive abrasion stages being chosen in a manner such that a granulometry which decreases from one stage to the other is achieved.